When the weather begins to get warm after it has snowed and the snow begins to melt, there are actually a number of complex and important physical processes taking place. Heat is absorbed and converts the snow particles into water, which then makes its way to the ground. A number of different important factors can determine the rate at which this snow melting process takes place.
Snow melting relies heavily on air temperature and the intensity of the sun. Other factors are also important to a lesser extent, like the speed and temperature of the wind and whether it is raining. The terrain on which the snow has fallen and its angle to the sun is also fundamental.
When the temperature begins to rise and the heat from the sun reaches the snow, the melting process begins. Because the top layer of snow is the first to receive this energy from the sun, snow melts from top to bottom. The energy in the heat turns the snow into water by breaking down the snow crystals. When the bonds holding these crystals together get too weak, they cannot overcome the forces of gravity, and drops begin to trickle to the ground. These first warm water drops also contribute to raising the temperature of the snow and speeding up the melting process.